A few ingredients:
1. Flying visit to Louvre to see the Giotto exhibition 2. A box of crayons lurking in bottom of overloaded bag 3. A fascinatingly textured East Coast placemat 4. An empty quiet carriage 5. A doodle to try out the crayons on the interestingly textured placemat, gradually taking on the form of a Giotto inspired face: those odd grey-green shadows emerging from the under painting.
Not quite the same effect with wax crayons. But technical and aesthetic deficiencies compensated for by murmurs of appreciation and admiration from the stewards passing to and fro.
This must be what it’s like to do chalk portraits on pavements.
The stewards think it’s wonderful. But I have to say, Giotto is in fact quite a bit better.